4Game

^{This is mainly to casual players or just people who've grown tired of the EFT's recoil and scavs.}
I've had A LOT of success with shotguns this wipe. Mainly Mossberg 590A1 since you can get that from Jaeger lvl1. It's also a decent shotgun for modding even in the early game (Go for high ergo, recoil is irrelevant with pump shotguns). A full modded Moss at trader lvl1 only has one barter which is a USB Adapter for the Magpul M-LOK Cantilever Mount or alternatively use a Magpul M-LOK AFG tactical foregrip if you have one.

Craft 12/70 8.5mm Magnum buckshot shells at Workbench lvl1 for 1x Classic matches and 1x Kite. These are REALLY good in the early game because of it's flesh damage and amount of pellets – armor penetration is bs but that's not the beauty of this ammo. It shoots 8 pellets each dealing 50 damage and if I'm not mistaken that's only about 2-3 pellets that needs to hit the head which is fairly easy because of the spread (assuming you're 30-40^{maybe 50} away from your target).

• Scavs almost never wear head protection and rarely anything better than Paca, 6B2 or BNTI Module-3M, so they're often a one shot which is REALLY good this wipe because of the AI Scav's new aimbot feature so you don't want to be exposed to their line of fire for more than a couple of seconds which is often what happens with full auto weapons like AKs or SMGs.
• Very few PMCs have good headgear this early in the wipe. Not to mention that what the helmets cover on your head is really important – a lot of class 3 and especially 4 helmets don't cover the ears ("Ears" covers basically the entire side of the head) which works really well with our high flesh damage pellets. Tbh, the Ratnik is the only thing you should be worried about.
  If you're in a cqc then go for their legs which also makes your character look down and decreases the chances of getting head,eyes'ed by a SMG or another shotgun.

Factory of course is a good map for shotguns but that map is mainly for shits and giggles.
The second best map imo is Customs. Customs has A LOT of choke points where you're going to have the upper hand: long walls/fences with only a few entrances, buildings making small alleyways and then of course the buildings themselves. New Gas station, Rauf Roadblock, Big Red and pretty much the entire construction area are all great places to hang out at. Can't speak for dorms cause lack of experience, I never go there that's a chad breeding ground.
A good tip for when to start blasting is if you can hear them walk or run while wearing a headset, then you can start shooting. If I remember correctly most headsets will pick up running footsteps from 35-50 meters away which is good range for a shotgun.
Ammo only needs to take up one to two slots. Mossberg's magazine has space for 8 shells so 8-16 should be more than enough to have in your pockets – then an additional 20 in your Secure Container just to be sure. This means for scav/pmc killing quests like "Operation Aquarius – Part 2" for scavs, you don't necessarily need a Rig or Backpack if you're just there to kill.

Hope someone out there will find this useful and if you have anything to add please do 🙂